VercelEngineering PostOfficial Source

Cline is now available in the AI SDK harness layer

Vercel’s AI SDK harness now runs Cline behind the same interface as six other coding-agent runtimes, while keeping Cline in the host and sandboxing only its tools.

Vercel · Aug 18, 2026

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Source Summary

The official **@ai-sdk/harness-cline** adapter runs Cline through the shared HarnessAgent interface. The harness layer now supports **seven runtimes**, including Claude Code, Codex, Cline, OpenCode, Pi, Deep Agents, and Grok Build.

Practical Implication

Builders maintaining agent products can put Cline behind the existing interface and compare or switch runtimes without rewriting application integration code. Review trust boundaries before assuming the entire runtime is isolated.

Agent-Ready Context

The official **@ai-sdk/harness-cline** adapter runs Cline through the shared HarnessAgent interface. The harness layer now supports **seven runtimes**, including Claude Code, Codex, Cline, OpenCode, Pi, Deep Agents, and Grok Build.

Builders maintaining agent products can put Cline behind the existing interface and compare or switch runtimes without rewriting application integration code. Review trust boundaries before assuming the entire runtime is isolated.

Cline itself runs in the **host process**; only its filesystem and shell tools operate in the sandbox, with no bridge installed there. The material does not specify behavioral parity between supported runtimes.

Connected Context · Feed7 Judgment

This confirms that HarnessAgent is becoming a practical runtime-selection layer, adding Cline as a seventh official option without requiring another application integration. It does not establish behavioral interchangeability, and it sharpens the security boundary: Cline remains in the host process while only filesystem and shell tools are sandboxed, so adopting the adapter must not be treated as full runtime isolation.

Grok Build is now available in the AI SDK harness layerBoth official adapters reinforce that one HarnessAgent integration can add or swap coding runtimes, while neither establishes parity in runtime-specific behavior.Use ACP-compatible harnesses with the AI SDK harness layerThe Cline adapter complements the generic ACP path: ACP broadens compatibility, while a dedicated adapter provides an official integration without proving identical controls or events.Vercel AI Gateway and Vercel Sandbox now available on Hermes AgentBoth separate where the agent runs from where commands execute, reinforcing that sandboxed tools do not automatically mean the whole agent runtime is isolated.github/copilot-sdkCopilot SDK exposes another embeddable coding runtime, but HarnessAgent targets cross-runtime application portability; both still leave permissions, authentication, and process boundaries as product responsibilities.

Context Map

toolscoding#coding-agents#agent-sdks#sandboxing

Uncertainty

Cline itself runs in the **host process**; only its filesystem and shell tools operate in the sandbox, with no bridge installed there. The material does not specify behavioral parity between supported runtimes.